d3_geo_voronoi_rs

rust 2021 edition.

Given a set of objects in spherical coordinates, it computes their Delaunay triangulation and its dual, the Voronoi diagram.

This is a port of the d3-geo-voronoi library into a RUST library.

It is part of a collection of d3 modules ported to rust.

• d3_geo_rs
• d3_delaunay_rs
• d3_geo_voronoi_rs

As a example the library can be used to compute the following delaunay mesh.

( computed from 6,000 points on a sphere selected at random )

Currently we have 84% test coverage ( as reported by cargo tarpaulin -o Html )

Performance Profiling

Demo Page

The original javascript library has a benchmark in the form of web page which records the number of frames displayed per second. For comparison the benchmark has been ported.

• javascript - d3-geo_voronoi/src/benchmark/sphereCanvas.html
• rust - rust_d3_geo_voronoi/benchmark.

Measuring the performance of a library is complicated, as different applications employing the library may see different results. Desktop and mobile performance may differ.

There are traditionally two way of measuring increases in performance :-

A) Speed: By asking how long it takes to perform a certain computation?

B) Throughput: By asking how much more work can I perform in a given time?

A and B are ideally linearly related, but often high throughput requires more memory which may increase page swapping. Javascript uses garbage collection, rust does not. In garbage collected environments, the dynamics of a collectors behaviors may cause the figures reported by A and B to diverge.

Here are the results for the benchmark :-

A) When I tune the benchmark for 60ps, I find the javascript can render 600 points in 16ms. The rust version performs the same workload in 8.165ms. ( a factor 1.95 speedup).

B) When I increase the number of points given to the RUST version to render, I find I can render 1220 in 16ms. An increase of just under 2.

I am currently looking to add more benchmarks, a diverse collection of example application code, will give greater confidence in what to expect.

Profile Target

This workspace contain a binary "profile_target" which outputs the result of a computation similar to that of the demo_page. Before API finalization - I am currently using cargo flame-graph to identify any obvious optimizations.

from rust_d3_geo_voronoi

cargo install  flamegraph
cargo flamegraph -- profile_target

Further Development

Considering migration 0.9.0 to 0.10.0. Many of the non idomatic "new" methods have been replaced with a TryFrom implementation. For more details see the CHANGELOG.md

Currently the demo works only then f64 is used as the floating point type. [For f32 the cell integrity is broken as some of the cell appear to take-up the whole sphere.] To be ported:-

contour.js and geo-contour-test.js

Currently there is a failing test suite geo_voronoi_test.rs "geoVoronoi.hull does not break on difficult polygons"

Instructions for building the benchmark

I'm using wasm pack to package the following packages into a single wasm file. rust_d3_geo, rust_d3_delaunay.

The application displays a delaunay mesh of a large number of cells onto a sphere.

To build and start the web server:-

cd benchmark\www
npm install
npm run start

The last command automatically starts your web browser.

For benchmarking, to obtain best performance

cd benchmark\www
npm run build
npm run serve